Our flash photolysis studies will continue to probe both the mechanisms for the control of heme reactivity as well as the process of ligand photorelease. We shall pursue the endor of copper proteins, through a comparative study of type I and type II centers. Our study of cytochrome c peroxidase and compound ES will involve endor of chemically modified proteins in order to confirm our identification of the radical site. Other protein and model systems will be studied. The study of cobalt-substituted cytochrome P-450 will be completed. We believe we have identified the axial ligand of both the ferro- and oxy-enzyme. We not have in hand large quantities of pure metal-hybrid hemoglobins. They will be used in the study of the Hb allosteric properties.